Window covering assemblies such as mechanical blinds usually are based on the same general overall design, namely a head rail device of rigid usually sheet metal material is provided, from which some form of blind or window covering is supported. Usually there is some form of mechanism within the head rail by means of which the blind may be operated between the open and closed positions.
Venetian blinds are one form of such a window covering assembly, and so-called "vertical" blinds are another form, and there are numerous other types of window coverings some involving blinds and others involving some form of moveable draperies such as balloons, "russians", and the like, all of which are usually supported by means of a similar horizontal rigid rail structure, usually known in the art as a "head rail".
Numerous different systems have been employed in the past for supporting such head rails. In some cases, supports are provided to engage the head rail intermediate its two ends, and in other cases supports are provided to engage the head rail at each end. In some cases, the supports are attachable to the wall, or the window frame and, in other cases, the supports may be attachable to a ceiling.
One particularly popular form of support, particularly in the case of venetian blinds, is a generally rectangular boxlike structure, which is provided in pairs, so that there is one such box structure at each end of the head rail. The two ends of the head rail are fitted inside the respective box structures, thereby supporting the blind or window covering in position. To facilitate erection of the blind, and also to facilitate removal of the blind for cleaning or servicing in the like, the boxlike structure usually is provided with an open side, and a door closure device is swingably mounted on the box structure so that it may swing between open and closed positions. Usually some form of simple retaining clip device is provided, engageable between the door and the box structure so that the door may be held closed to retain the end of the head rail in the box.
One particularly popular form of such a boxlike supporting device has been in wide use for supporting venetian blinds. It was made of sheet metal, bent into an open-sided boxlike configuration, and it was provided with a door with a spring clip. Two such boxlike structures were required--one at each end of the head rail.
However, the design of this particularly popular boxlike support device was such that the spring clip lock and the box itself were designed as right and left hand structures. Consequently, it was necessary to have two sets of tooling for manufacturing the two different boxlike structures--one for the right hand, and one for the left hand end. It was then necessary for the manufacturer to stock such supporting structures as right and left hand pairs. It was necessary for the manufacturer to ensure that with every order of blinds that were shipped to a customer, the boxlike supporting ends were shipped in right and left hand pairs.
It was also necessary for the manufacturer to provide complete installation instructions so as to ensure that the supports were erected at the appropriate ends of each blind head rail, since if they were erected the wrong way round, the head rail could not be installed.
All of these disadvantages of this well known popular form of blind support have been known for many years. However, it still remains essentially standard throughout the industry.
In addition to all of these disadvantages, the window covering industry is constantly seeking ways to improve the aesthetic appearance of window coverings and blinds. One way in which this is achieved, particularly with venetian blinds, for example, is to attempt to provide a front cover for the head rail. This front cover is usually provided by means of one or, in some cases, two additional blind slats, which are held in clips extending across the front face of the head rail. This practice has also become virtually standard throughout the industry. However, the design of the rectangular box type of left and right hand end support structures requires that they must fit around the exterior of the head rail at each end, in order to retain it in position. Any form of front covering such as additional blind slats, which is attached to the front of the head rail, must then also be offset forwardly from the front of the head rail sufficient to provide clearance in front of the end supports as well as the head rail.
In addition to this, when it is desired to remove the blind head rail from the end supports for service, it is necessary to first of all remove the slats providing the front covering, in order to have access to the doors on the end supports.
Consequently, whatever structure is provided for supporting the blind slats on the front of the head rail, must be designed in such a way that it can readily be removed and replaced.
In practice, this has proved to be somewhat difficult, and it is not unusual to find that the blind slats on the front of the head rail are somewhat insecure and are easily dislodged during operation of the blind.